The present invention relates to an image stabilization apparatus which corrects image shake in an optical apparatus such as a camera.
Image stabilization apparatus is configured by, for example, of a shake detection system which includes a shake sensor and a shift mechanism which shifts a correction optical system or an image-pickup element in a direction orthogonal to the optical axis or the like in response to detected shakes.
In recent years, thin cameras with great portability have been proposed which include an optical system referred to as a bending optical system and having an optical axis bent 90 degrees by a prism or a mirror.
Japanese Patent Laid-Open No. H02(1990)-66536 has disclosed an image stabilization apparatus in which a correction optical system is cantilever-supported by at least three flexible (elastic) supporting rods extending in parallel with an optical axis and having equal lengths.
Japanese Patent Laid-Open No. 2002-207148 has disclosed an image stabilization apparatus in which an image-pickup lens member is supported movably in a direction orthogonal to an optical axis by fixing one ends of four flexible members in the optical axis direction to the image-pickup lens member and securing the other ends thereof to a substrate.
In these publications, plural flexible members for supporting the correction optical system are arranged at equal angular intervals about the optical axis and at uniform distances in the diameter direction. For example, in the apparatus disclosed in Japanese Patent Laid-Open No. H02(1990)-66536, the three flexible members are disposed at equal angular intervals of 120 degrees to form the vertexes of a regular triangle around the optical axis. In the apparatus disclosed in Japanese Patent Laid-Open No. 2002-207148, the four flexible members are arranged symmetrically with respect to the optical axis, that is, at the corners of a square.
In the apparatuses disclosed in the abovementioned publications, an actuator is placed such that the vector of drive force of the actuator (or the extension thereof) for shifting the correction optical system passes through the optical axis.
When the image stabilization apparatus is incorporated in a camera which includes the bending optical system for satisfying the requirement of a thinner shape, the intended thinner shape may be inhibited by arranging the plural flexible members for supporting the correction optical system such that the members form the vertexes of a regular triangle or the corners of a square. It is thus preferable to arrange the plural flexible members such that they form the corners of a rectangle.
Carelessly changing the arrangement of the flexible members, however, may prevent the vector of drive force produced by the actuator from overlapping with the vector of restorative force of the flexible members to generate torque in the plane orthogonal to the optical axis of the correction optical system.
As a result, it is conceivable that an unnecessary rotational motion is produced as well as an essentially necessary translation motion of the correction optical system to reduce the accuracy of image stabilization (that is, image shake correction).